Flood Vulnerability Assessment (Yampi Sound)

Client:

JJL for the Department of Defence

location:

Derby, WA

overview

Flood Vulnerability Assessment for Yampi Sound Road Crossing

The Yampi Sound Training Area, north of Derby WA, is a remote facility with significant access difficulties, unique environmental constraints and extremely high natural heritage value. Improving access, via a sealed road, was an identified need to aid better use of the facility. As the region is susceptible to extremes of weather, and has large floodplain areas, a flood vulnerability assessment was required.

For approximately 60km, Kimbolton Road crosses black soils, claypan and alluvial material traversing floodplains and river crossings, which becomes impassable in the wet season.

Pritchard Francis were engaged by JLL as lead consultant, with Water Technology as sub consultants, to carry out a Feasibility study of constructing 70km of sealed road along the Kimbolton Road track from Gibb River Road, approximately 40km from Derby, Western Australia, to Department of Defence training grounds in West Kimberley.

The project team carried out a feasibility study for the road construction, including the preliminary design of road pavement, river crossing options, possible track realignment, coordination of the geotechnical scope and for the road construction, borrow pit location investigations and fill material requirements.

Flood Vulnerability Assessment

Water Technology completed flood modelling of the entire floodplain to assess the vulnerability of the road to catchment and storm tide flooding and to assist in the design of river and creek crossings. Coastal tide and storm surge analysis was also completed to locate sections of the road subject to inundation from coastal conditions. To assess the impacts of tidal inundation, both astronomical and storm tide were investigated to produce tide levels for different scenarios. These levels were compared to the surveyed road level to locate areas that are vulnerable to tidal inundation and to recommend locations for floodways or bridges.